mamaku, black tree fern
Cyathea medullaris (G. Forst.) Sw.; Cyathea medullaris var. polyneuron (Colenso) C.Chr.; Cyathea medullaris var. integra Hook.; Cyathea polyneuron Colenso; Polypodium medullare G.Forst.;
Vascular – Native
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
2n = 138
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – an interim threat classification status has not been assessed by the NZTCS panel.
- Conservation status of New Zealand indigenous vascular plants, 2017 . 2018. Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley. Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | Not Threatened
Previous conservation statuses
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Large tree fern with black-stalked leaves to 5m long. Trunk with obvious scars from old leaves, to 20m tall. Leaf stems covered in small scales that have a spiny edge (lens needed). Sporangia arranged in small round capsules underneath leaves.
Indigenous. Occurring form the Three Kings Islands south to Stewart and the main Chatham Islands. Uncommon in the drier eastern portion of the South Island, and apparently absent from Canterbury and Otago.
Common in lowland forest throughout the North Island. Primarily in wetter coastal areas of the South Island.
Wetland plant indicator status rating
FACW: Facultative Wetland
Usually is a hydrophyte but occasionally found in uplands (non-wetlands).
Tree fern up to 20 m tall. Trunk black covered with hexagonal stipe bases. Stipes thick, black, harsh to touch, covered in black scales. Scales with marginal spines. Fronds up to 5 m long, arching upwards from crown, 3-pinnate, leathery, dead fronds falling (except in very young plants). Longest primary pinnae 0.4-1 m long, undersurfaces bearing scales with marginal spines. Indusia completely covering sori at maturity, splitting irregularly.
Easily recognised by trunk with its distinctive hexagonal stipe scars and by the scales which possess marginal spines.
None (spore bearing)
None (spore bearing)
Minute spores are wind dispersed (Thorsen et al., 2009).
Can be grown from fresh spores (but slow). Young plants transplant easily and freshly felled trunks will usually resprout if planted and carefully watered. Easy, once established in a variety of conditions. Should not be removed from the wild unless with landowner permission.
medullaris: Pithy (trunk)
Where To Buy
Commonly cultivated. Not as freely available from nurseries as other tree ferns because it is slow from spores and sporelings are notorious for failing following transplants.
Fact sheet prepared for NZPCN by P.J. de Lange March 2004. Description adapted from Brownsey & Smith-Dodsworth (2000).
References and further reading
Brownsey, P.J.; Smith-Dodsworth, J.C. 2000: New Zealand Ferns and Allied Plants. Auckland, David Bateman
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Sphaeropteris medullaris Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/sphaeropteris-medullaris/ (Date website was queried)